Article (Scientific journals)
Lack of isocitrate lyase in Chlamydomonas leads to changes in carbon metabolism and in the response to oxidative stress under mixotrophic growth.
Plancke, Charlotte; Vigeolas, Hélène; Hohner, Ricarda et al.
2014In Plant Journal, 77 (3), p. 404-417
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Keywords :
Chlamydomonas; carbon metabolism; glyoxylate cycle; isocitrate lyase; mixotrophic growth; mutant; oxidative stress
Abstract :
[en] Isocitrate lyase is a key enzyme of the glyoxylate cycle. This cycle plays an essential role in cell growth on acetate, and is important for gluconeogenesis as it bypasses the two oxidative steps of the tricarboxylic acid (TCA) cycle in which CO2 is evolved. In this paper, a null icl mutant of the green microalga Chlamydomonas reinhardtii is described. Our data show that isocitrate lyase is required for growth in darkness on acetate (heterotrophic conditions), as well as for efficient growth in the light when acetate is supplied (mixotrophic conditions). Under these latter conditions, reduced acetate assimilation and concomitant reduced respiration occur, and biomass composition analysis reveals an increase in total fatty acid content, including neutral lipids and free fatty acids. Quantitative proteomic analysis by 14 N/15 N labelling was performed, and more than 1600 proteins were identified. These analyses reveal a strong decrease in the amounts of enzymes of the glyoxylate cycle and gluconeogenesis in parallel with a shift of the TCA cycle towards amino acid synthesis, accompanied by an increase in free amino acids. The decrease of the glyoxylate cycle and gluconeogenesis, as well as the decrease in enzymes involved in beta-oxidation of fatty acids in the icl mutant are probably major factors that contribute to remodelling of lipids in the icl mutant. These modifications are probably responsible for the elevation of the response to oxidative stress, with significantly augmented levels and activities of superoxide dismutase and ascorbate peroxidase, and increased resistance to paraquat.
Disciplines :
Biochemistry, biophysics & molecular biology
Genetics & genetic processes
Author, co-author :
Plancke, Charlotte
Vigeolas, Hélène ;  Université de Liège - ULiège > Département des sciences de la vie > Génétique
Hohner, Ricarda
Roberty, Stéphane  ;  Université de Liège - ULiège > Département des sciences de la vie > Génétique
Emonds-Alt, Barbara ;  Université de Liège - ULiège > Département des sciences de la vie > Génétique
Larosa, Véronique ;  Université de Liège - ULiège > Département des sciences de la vie > Génétique
Willamme, Rémi ;  Université de Liège - ULiège > Département des sciences de la vie > Génétique et Physiologie des Microalgues
Duby, Franceline ;  Université de Liège - ULiège > Département des sciences de la vie > Génétique
Onga Dhali, David
Thonart, Philippe ;  Université de Liège - ULiège > Département des sciences de la vie > Biochimie et microbiologie industrielles
Hiligsmann, Serge ;  Université de Liège - ULiège > Département des sciences de la vie > Biochimie et microbiologie industrielles
Franck, Fabrice ;  Université de Liège - ULiège > Labo de Bioénergétique
Eppe, Gauthier  ;  Université de Liège - ULiège > Département de chimie (sciences) > Chimie analytique inorganique
Cardol, Pierre  ;  Université de Liège - ULiège > Département des sciences de la vie > Génétique et Physiologie des Microalgues
Hippler, Michael
Remacle, Claire  ;  Université de Liège - ULiège > Département des sciences de la vie > Génétique et Physiologie des Microalgues
More authors (6 more) Less
Language :
English
Title :
Lack of isocitrate lyase in Chlamydomonas leads to changes in carbon metabolism and in the response to oxidative stress under mixotrophic growth.
Publication date :
2014
Journal title :
Plant Journal
ISSN :
0960-7412
eISSN :
1365-313X
Publisher :
Blackwell, Oxford, United Kingdom
Volume :
77
Issue :
3
Pages :
404-417
Peer reviewed :
Peer Reviewed verified by ORBi
Commentary :
(c) 2013 The Authors The Plant Journal (c) 2013 John Wiley & Sons Ltd.
Available on ORBi :
since 18 February 2014

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